Tmobile phone on Cricket

I've just switched over my CDMA account to a GSM Cricket account. I used my Tmobile phone, a Samsung Galaxy Light (SGH-T399) to do a byod. My service works but I had a few questions that I've already asked multiple Cricket employees at different stores and even online. No one seems to know. Firstly, my data won't work unless roaming data is checked. The roaming doesn't cause me any extra charges it's just annoying. The roaming clock comes on my lock screen and my phone says Roaming in the Status section of About Phone. The roaming icon by the signal strength indicator doesn't show. I know how to turn the roaming clock off but that isn't the problem. I just wonder why it's in roaming. Next, my data says 3G but I'm getting speeds at 8 Mbps. I know it's closer to LTE speeds so I'm not sure what is happening there. AT&T uses Band 17 for their main LTE and I'm on LTE right now. Why isn't my LTE icon lit up? My phone supports LTE band AWS and Band 17. Is Cricket preventing LTE use on Band 17 and switched it to a diff frequency? Is the constant roaming causing some kind of issue? Lastly, my phone lets me switch to GSM which is Edge. That's low speed data. With Tmobile I switched my high speed data off and used Edge to save data from my high speed monthly allotment. It is low speed and didn't count against my allotment. With Cricket my low speed data on Edge is deducting from my high speed allotment. I don't find that to be fair as Cricket says on their website they sell you a high speed data bundle. Seems in reality it's just deducting from your first bundle of that data be it high speed or low speed. I think that's false advertising and a load of nonsense. I like to switch my data to low speed to conserve high speed for when I need it since it's unlimited after the allotment. So what's up with that?